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Oct 27, 2001, 02:08 AM
Mike Swan

What would be some good parameters for a direct drive 280 6v plane?


Looking at scratchbuilding a fighter for 280 6v direct drive,namely a f4f wildcat,its a pretty pudgy little plane for 280 direct,would tops be about 1/24,everything in my stable is spd400 or bigger,well except for the mandatory litesticks,so im covering new ground here,im working off of a three view and trying to figure out size and wing area and still remain fairly scale,ive looked at the web and searches and usually end up back at hobby lobbys page,are their weights and data on the direct drive motors pretty close. Thanks Mike. Well after spending alot of time on motocalc it looks like its not going to happen unless i go geared,according to motocalc with direct drive id be wasting most of my batts and the plane would never get on step.
Last edited by kit basher; Oct 27, 2001 at 10:37 AM.
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Oct 27, 2001, 12:49 PM
Registered User
Kevin Murray's Avatar
Kitbasher - I would recomend adding a gear drive to the 280, especialy in a plane that has a large diamiter fuselage.
The BB grarboxes from HL are nicely made, come in 3 ratios, only add 0.6 oz to your plane and are a good deal at $13.

As for sizes - look at the Herr Breezy Day Pakr Flyers. They are for sp 280's. 35.75 wingspan. 214 sq in area. weight 9 oz.
That gives a starting point. You ill need very light balsa.
Oct 29, 2001, 04:12 AM
Master
ChrisP's Avatar
I picked up a Graupner Tipsy (which is designed for a direct drive Speed 280 6v) a few weeks ago and had the motor on my test rig this weekend. I had previously felt that a direct drive 280 model wouldn't be up to much, but I thought I would give one a try just for fun. Certainly a completely different animal than my Bloody Mary with its geared 300 which has awesome performance !!!

According to local 'folklore' the Günther plastic (ex-Twinstar/Pico Jet) prop is better than the recommended Graupner one. I bought a decent adapter and drilled out the prop hub to fit it as I had heard rumours of 280's throwing Günther props with the original rubber hub.
I have 6x700 mAh NiMH Twicells for the power supply and the motor pulls a measured 3.7A @ 6.6v with this set up. Assuming an efficiency of about 65% this means there is about 16 Watts of power at the prop. This will also be my first model with NiMH cells which was another reason to build it.
Graupner recommends a 'not to exceed weight' of 300 gms for the Tipsy, but I will do all I can to keep it low. 300 gms sounds heavy to me for 16 Watts, but I'll keep judgement until I've flown the model.

I noticed there are at least 3 Speed 280's on the German market - the Graupner, the Jamara black version and the Aeronaut 280 BB which costs three times as much as the Graupner/Jamara motors. I must investigate why !!

Hope the numbers help !!

PS - Regarding warplanes with 280's - I am currently mulling over the idea of doing a twin or 4-engined.

ChrisP
Oct 29, 2001, 08:42 AM
Master
ChrisP's Avatar
https://www.rcgroups.com/forums/show...threadid=15435

Seems you would have a much better chance with the 280BB than the regular 280 - see info from Bill Glover.

ChrisP
Oct 29, 2001, 10:14 PM
Registered User
Kevin Murray's Avatar
Chris - The bb version is 3 times the price becauce the power is much higher, approaching Sp 400 terratory. Also has replacable brushes. And the obvious one , BB insted of bushings.

A quality motor vs a desposable one.
Oct 29, 2001, 10:20 PM
Registered User
Try a direct drive 6 * 3 (I've used the Graupner folder), it worked well on my slowflyer (The Pooch)

Heather
Oct 29, 2001, 11:36 PM
Registered User
Jurgen Heilig's Avatar
@Chris: Why do you want to use 7 instead of 6 cells? You won`t be able to balance the Tipsy without adding some weight to the tail. If you want more power, use the 280 RACE. Jürgen


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